钢铁钒钛

Study on Preparation of Metatitanic Acid by Hydrolysis in the Process of Producing Titanium Dioxide by Decomposition of Titanium Slag with Alkali Molten Salt

Han Yanfang, Sun Tichang, Xu Chengyan, Qu Jingkui, Qi Tao, Wang Guiling

2012, 33(3): 1-5.

Abstract(21) PDF(1)

Abstract:
Preparation of TiO₂ with titanium slag by molten-salt method is a new way to produce TiO₂ in which the preparation of metatitanic acid by hydrolysis is an important step due to its huge influence on the quality and yield of the finished products.This paper has identified the factors including concentration of titanium solution,F value and hydrolysis time that influence the grain size and conversion ratio of the metatitanic acid.The results show that the hydrolysis ratio of the titanium solution under different temperatures remains relatively low during the initial 30 min,and after 50 min it rises quickly while after 100 min,the variation of the hydrolysis ratio with time becomes milder.With the increase of temperature,the F value becomes lower,and with the decrease of the concentration of titanium solution,hydrolysis reaction proceeds faster and a higher ultimate conversion ratio can be obtained as a result.At the beginning,the grain size of the metatitanic acid resulting from hydrolysis increases with the time of the hydrolysis reaction.Three hours later,the grain size of the metatitanic acid exhibits a little fluctuation with time.The grain diameter of the metatitanic acid decreases with the increase of the concentration of titanium solution and F value and increases with better stability of the titanium solution.During preparation of metatitanic acid in the new TiO₂ pigment production process,the TiO₂ concentration and F value should be controlled at about 200 g/L and 1.8 ～ 1.9 respectively,and hydrolysis process should be carried out for 4 hours under the condition of slight boiling.

Influence of Vanadium Slag Cooling Scheme on Particle Size of Vanadium Spinel and Sodium Roasting

Fu Zibi, Yin Danfeng, Zhang Xinxia

2012, 33(3): 6-10.

Abstract(20) PDF(1)

Abstract:
Phase structures and spinels’ particle size of water-cooled vanadium slag,air-cooled vanadium slag and slowly cooled vanadium slag are analyzed,and the effect of holding time at 1 000 ℃ under nitrogen atmosphere on particle size of the vanadium spinel is studied.In addition,comparisons of sodium roasting of water-cooled vanadium slag,air-cooled vanadium slag and slowly cooled vanadium slag under the same conditions are made.According to the research,slow cooling and holding at 1 000 ℃ benefits the growth of vanadium spinel particles;for the vanadium slag of-0.125 mm roasted without vanadium extraction tailings,the conversion rate of water-cooled vanadium slag at different size range is 1%~2% lower than that of slowly cooled vanadium slag at the same size range;for the vanadium slag of-0.125 mm roasted with vanadium extraction tailings,the conversion rate of water-cooled vanadium slag is 0.56% lower than that of slowly cooled vanadium.

Study on Quality Improvement of Vanadium Precipitation with （NH₄）₂SO₄

CHEN Zi-qing

2012, 33(3): 11-15.

Abstract(21) PDF(1)

Abstract:
The optimization of process parameters and control measures during the process of vanadium precipitation with acidic ammonium is studied to improve the quality of feedstocks for the production of high grade V₂O₃.Major factors contributing to the quality of APV prepared by vanadium precipitation with acidic ammonium are investigated,such as concentration of vanadate leaching solution,adding amount of ammonium salt,temperature of vanadium precipitation,reaction time,pH value,stirring conditions and washing condition of the plate and frame filter press.The results indicate that impurities in the precipitated APV can be reduced with the concentration of vanadate leaching solution at 25 to 35 g/L,two-step acid adding process,final precipitating temperature of 95 ℃,reaction time of about 35 min,washing time of filter cake for 20 min,temperature of washing water at about 75 ℃,the blowing time during pressing for 80 min,wind pressure of no less than 0.5 MPa,and cake thickness of no more than 25 mm etc.

Study on Recycling Waste Water from V₂O₅ Extraction from the Stone Coal Leaching Solution

Huang Han, Zeng Lunsheng, Liang Huanlong, Luo Siqiang, Lei Weiming

2012, 33(3): 16-19.

Abstract(24) PDF(1)

Abstract:
Experiments for recycling waste water from the process of V₂O₅ extraction from stone coal leaching solution are carried out in which a V₂O₅ extraction process of direct acid leaching and solvent extraction is employed using stone coal obtained from a certain area of Guangxi Province as raw materials.Impurities（Si,Fe and Al etc.） formed in leaching solution and their influence on process index and product quality during wastewater recycling process are investigated.Results show that the leaching rate of vanadium is not remarkably affected by utilization of the recycled residual solution from extraction.Si does not accumulate while Fe and Al accumulate to a certain extent and then stabilize during recycling process,which exerts no influence on recycling of the waste water.The vanadium pentoxide produced steadily can meet the requirements of GB3238-1987（V₂O₅-98）,which shows the product quality is not remarkably impacted by the recycling of residual solution.

Discussion on Routes of Recycling Waste Water Produced from APV Precipitation with Acidic Ammonium Salts

WANG Ying

2012, 33(3): 20-23.

Abstract(22) PDF(1)

Abstract:
Routes of recycling waster water produced from APV precipitation with acidic ammonium salts are proposed,which is expected to be used for rinsing precipitation equipment,washing tailings and leaching roasted materials and corresponding experiments are carried out.The experimental results show that use of waste water for rinsing precipitation equipment can effectively solve the problem of APV redissolution as vanadium concentration of APV is less than 0.15 g/L in the solution with pH value of 2.5~3.5,thus reducing vanadium loss.Using waste water instead of production water offers a better option to wash tailings when washing is conducted at 90 ℃ above,with liquid/solid ratio more than 2.5,for more than 3 times and at least 45 minutes each time.Using waste water for leaching roasted materials is practicable and the leached solution is more desirable for dephosphorization.

Investigative Test of Iron Separation Process of a Panzhihua Lower Grade Vanadium-bearing Titanomagnetite Ore

Zeng Zhiyong

2012, 33(3): 24-27,39.

Abstract(21) PDF(1)

Abstract:
Investigative test of iron separation process of a kind of Panzhihua lower grade vanadium-bearing titanomagnetite ore,including crushing,grinding and magnetic separation were carried out.Two options were tested:（a） treat the ore by grinding and magnetic separation after crushing;（b） enrich the ore by pre-magnetic separation after crushing,then treat the concentrate by grinding and magnetic separation.The results show that the ore with average iron content of 17.79% can be crushed from 500~30 mm to 25 mm below by three steps of crushing;then it can be grinded and separated,or pre-magnetic separated before grinding and separation to obtain concentrate with iron content higher than 56%.In the case of pre-magnetic separation,iron content of the ore before grinding and separation can be increased to 19.57% with amount of material consumption reduced by 33.54%.

Numerical Simulation on Cooling Dynamics of Slag Droplet Granulated by Gas Quenching

Lu Hongwei, Li Junguo, Zhang Yuzhu

2012, 33(3): 28-33.

Abstract(25) PDF(1)

Abstract:
Steel slag droplets will experience a complex process of cooling and solidification after they are granulated by gas quenching.Numerical simulation for cooling dynamics of slag droplets is carried out by Fluent software.The simulation result is compared with that obtained from numerical calculation.It is suggested that the slag droplet undergoes three cooling phases including liquid cooling,release of latent heat and solid cooling.Without considering subcooling degree during solidification of the slag droplet,the consuming time during liquid cooling phase is short through Fluent simulation,while those during release of latent heat and solid cooling phase are long.The shell formation process can be simulated through Fluent software,while the consuming time during liquid cooling,release of latent heat and solid cooling phase can be calculated by numerical calculation.In summary,the total consuming time for cooling from 1 723 K to 1 073 K can be predetermined accurately by both Fluent numerical simulation and numerical calculation,which lay a theoretical foundation for gas quenching process of molten steel slag.

Numerical Simulation of Slag Entrainment by Vortex Flux During Tapping at Converter

Wang Jianqiang, Li Junguo, Han Zhijie

2012, 33(3): 34-39.

Abstract(23) PDF(2)

Abstract:
In order to effectively reduce the quantity of slag entrained into ladle during tapping and improve steel quality,a more efficient and low-cost method of slag stopping should be developed.In this paper,numerical simulation for static tapping process under different original molten steel levels has been computed by pressure based segregated implicit solver and k-ε turbulence model in commercial software Fluent 6.3.Under different original molten steel levels in the converter,formation time and movement of vortex flux and the flow characteristics of molten steel during tapping are illuminated in the aspect of numerical simulation by analyzing the flow field of molten steel.The research on slag entrainment during tapping,as well as simulation of tapping and vortex deforming,is expected to provide researchers with useful guidance in exploring advanced slag stopping technology.

Water Simulation of Steel/Slag Interface Flow Regime of the Slab Mould

Shu Zhihao, Hou Zewang

2012, 33(3): 40-45.

Abstract(13) PDF(1)

Abstract:
Based on a full-size water mould,the influences of the process parameters on the flow regime of steel/slag interface of the slab mould,such as the mould width,casting speed,SEN structure、submergence depth of SEN,etc were investigated.The results show that interfacial fluctuations and the max fluid rates at slag/steel interface increases with the augment of the mould width or casting speed,while the influence of SEN structure and submergence depth of SEN on interfacial fluctuations and the max fluid rates at slag/steel interface is complicated.It is concluded that the convex type SEN with an outlet angle of 15° has better universality.

Research on Characteristics of the Dead Zones in RH Melt Bath with Simulation Methods

Xue Liqiang, He Ping

2012, 33(3): 46-52.

Abstract(22) PDF(1)

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Taking the 170 t RH refining equipment of a steel company as a prototype,a mathematical simulation of flow field in the RH is carried out to study the dead zones in the RH melt bath under different gas flow rates,inner diameter and immersion depth of snorkel and vacuum degree.The results show that there are three dead zones at the top of ladle.With the increase of gas flow rate,the dead zones 1^# and 3^# get smaller rapidly and the zone 2^# gets larger at the beginning until the largest zone appears at 100 m³/h and then becomes smaller;with the increase of the diameter of snorkel,all the 3 dead zones get smaller and a long narrow dead zone forms below the two snorkels in zone 2#;the deeper the snorkel inserts,the larger the dead zones get and the more steady the surface of the ladle becomes.Among these operational parameters contributing to decreasing dead zones,the gas flow rate is the most influential factor,while the vacuum degree is the least.

Analysis on Multi-taper Billet Mould

Zhang Haihui, Liu Jianmin, Liu Zengxun, An Zhenliang

2012, 33(3): 53-58.

Abstract(14) PDF(1)

Abstract:
Based on stress inheriting characteristic of the billet shell in continuous casting,a thermo-mechanical coupling model of billet is established.Heat transfer and stress fields of the billet in the mould is analyzed by the finite element software ANSYS.The mould taper is optimized according to principle of minimum air gap and the influence of single-taper and multi-taper on solidification behavior of the billet shell in the mould is analyzed.The results show that under these two tapers,the solidification behaviors are obviously different in the corner area of the billet but basically the same in the central area.In the single-taper mould,the air gap spreads widely and heat flow remarkably reduces in the corner area;"hot spots" appear at the area around 12~22 mm away from the corner.In the multi-taper mould,the width and distribution of air gap significantly decrease and there are no "hot spots" in existence,which demonstrates multi-taper mould is more consistent with the solidification shrinkage law of the billet shell.

Research on Behavior of Non-metallic Inclusions in Non-oriented Silicon Steel During Refining Process

Liu Jingjing, Qin Zhe, Hou Zewang, Qiu Shengtao, Wang Janjun

2012, 33(3): 59-64.

Abstract(30) PDF(1)

Abstract:
During the refining process,the transformation of non-metallic inclusions in non-oriented silicon steel produced by the process of KR-BOF-RH-ASP is analyzed using the methods of SEM-EDS and main sources of non-metallic inclusions are identified in this paper.The results show that the inclusions after RH process are mainly Al₂O₃ and sulfides at l μm;then in the tundish,the amount of Al₂O₃ in the sample remarkably decreases while compound inclusions containing CaS,MgO-Al₂O₃ and sulfides increase to a certain extent,sizes of inclusions in different working sections are mainly at 0.5~3 μm.

Evolution of Hot Rolled,Normalized and Cold Rolled Texture of Non-Oriented Silicon Steel Produced by CSP

Pu Chunlei, Li Jianjun, Yue Erbin, Song Lin

2012, 33(3): 65-69.

Abstract(25) PDF(1)

Abstract:
By using EBSD and X-ray diffraction technology,evolution of hot rolled,normalized and cold rolled textures of non-oriented silicon steel produced by a simulation process of CSP was examined.The results show that the texture types along the thickness in the hot rolled strip are substantially different,including B-fibrous texture,A-fibrous texture and rotated cube texture of {001}＜110＞ in the surface,subsurface and center layer of the hot rolled plate respectively.The difference is weakened in the normalizing process,but cube texture of {001}＜100＞ with certain strength remains in the center layer of the normalized plate.Both surface and center layer of the cold rolled plate consist of B-and A textures with {223}＜110＞ and {111}＜112＞ as their major textures respectively.Analysis shows the evolution of texture is mainly determined by the initial texture and microstructure.

Effects of Production Process and Chemical Compositions on Magnetic Properties of Phosphorus-bearing Non- oriented Silicon Steel

Zhang Feng, Lv Xuejun, Ma Changsong, Chen Xiao

2012, 33(3): 70-76.

Abstract(15) PDF(1)

Abstract:
Based on industrialization of low and medium grade non-oriented silicon steel,the effects of production process and chemical compositions on magnetic properties of phosphorus-bearing non-oriented silicon steel are investigated.The results show that phosphorus could restrain the recrystallization of hot rolled strips and decrease the grain size of finished steel sheets.Thus,phosphorus can remarkably influence magnetic properties of non-oriented silicon steel.For aluminum free steel,the magnetic induction changes little but the iron loss increases gradually with the increase of phosphorus before and after SRA.For aluminum-bearing steel,no matter the silicon content is high or low,the magnetic induction decreases rapidly and continuously with the increase of phosphorus under the same conditions.However,the effects of phosphorus content on the iron loss are gradually weakened with the increase of silicon content.After the intermediate annealing process,a small amount of phosphorus could effectively improve the magnetic induction but result in little iron loss.

Research on High Temperature Ductility of 1.2%Si Cold Rolled Non-oriented Electrical Steel Slab

Hu Shaodong, Xiang Li, Lai Chaobin, Qiu Shengtao, Jia Caixia, Xie Senlin

2012, 33(3): 77-81.

Abstract(21) PDF(1)

Abstract:
High temperature ductility test for 1.2% Si cold-rolled non-oriented electrical steel slab at 600~1 300 ℃ has been carried out by Gleeble1500 stress/strain thermomechanical simulator.Thermoplasticity and intensity curve of samples under testing temperatures was obtained,then through the observation of inclusions in the brittleness area and the fracture surface of samples at different temperatures,the mechanism of the brittle fracture in its brittleness temperature zone was analyzed.The results show that there exist a brittleness temperature zone Ⅰ at above 1 220 ℃ and a low-plasticity temperature zone between 600 ℃ and 780 ℃ in 1.2% Si cold-rolled non-oriented electrical steel slab at strain rate of 1.0×10^-3s^-1 and test temperature of 600~1 300 ℃.One reason for the decrease of plasticity of 1.2% Si cold-rolled non-oriented electrical steel at the temperature between 600 ℃ and 780 ℃ is that it is very difficult to recrystallize,and another is the existence of AlN from ferrite in low temperature zone and crystal embitterment due to the precipitation of aluminosilicate.

Evolution of Microstructure and Texture of 50W1300 Non-oriented Silicon Steels

Jia Caixia, Xiang Li, Tang Guangbo, Qiu Shengtao, Zhao Hongjin

2012, 33(3): 82-87.

Abstract(39) PDF(1)

Abstract:
The effect of hot continuous rolling-cold rolling-annealing process on microstructure and texture of 50W1300 non-oriented silicon steel is investigated by the technology of EBSD and electron microscopy.The results show that during thermoplastic processing,all the grains in the surface layer of hot-rolled plates are equiaxed crystal and the grains in their cores are deformed flattened structure.The hot-rolled microstructure is transformed to flattened banded structure with characteristics of fibrous structure in the core after cold rolling.The annealed structure is composed of equiaxed ferrite grains with distinct and regular boundary.The texture distribution of hot rolled plates along the thickness are different while texture of cold rolled plate are basically the same,mainly consisting of α texture,γ texture and rotated cube texture of {100} ＜110＞.At the 1/4 thickness of the plate,the strength of α texture and rotated cube texture reaches the highest level while the strength of the γ texture decreases remarkably.The strength of γ-texture is weakened to some extent in the annealed plates.

Study on Thermal Deformation Behavior of 65Mn Steel for Saw Blade

Chen Liansheng, Liu Song, Song Jinying, Tian Yaqiang

2012, 33(3): 88-92.

Abstract(37) PDF(3)

Abstract:
The thermal deformation behavior of 65Mn steel for saw blade is investigated through thermocompression method with Gleeble-3500 thermal mechanical simulator.The results show that in a certain testing condition,the deformation resistance as well as peak strain of the 65Mn steel increases with the decrease of temperature and the increase of strain rate.A mathematical model for the 65Mn steel is established with its high fitting precision proved by regression analysis.

Research on non-metallic inclusions of 20G Steel

Gao Jü, Li Lijie

2012, 33(3): 93-97.

Abstract(17) PDF(1)

Abstract:
In the early production of 20G in Steel,crack defects and macro examination unqualified.So the type,resource,amount and distribution of non-inclusions are systemically studied by the actual combination of laboratory and field research methods for the production process of 20G steel,The result shows: Volume ratio of micro-inclusion is 0.149%and 0.184% in normal and casting clab;The content of macro-inclusion in normal and casting clab is 1.81 mg/kg and 3.31 mg/kg.Inclusions are mainly derived from the mold surface with the flux,followed by Tundish complex agent and slag ladle complex.

Latest Development of New Vanadium Materials

Wang Zhonghang, Zheng Shili, Du Hao, Wang Shaona, Zhang Yi

2012, 33(3): 98-106.

Abstract(16) PDF(1)

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As an important strategic metal resource for a country,vanadium and its compounds are widely used in metallurgy,aerospace,chemical and other fields.In recent years,as pressures on human beings in resources,energy and environment gradually increase,more and more researches have been made on vanadium materials applied in the fields of energy storage and environment protection,which results in the emergence of a large number of vanadium electrode materials,vanadium pigments,vanadium catalyst with high performance.However,high cost of vanadium materials is a major obstacle for its industrialization.Fortunately,the development and perfection of the nanotechnology and bio-medical technology make it possible to develop new environmentally friendly high-performance vanadium materials with lower cost,which will greatly expand the applications of vanadium materials and bring a promising future.

2012, 33(3): 107-108.

Abstract(15) PDF(1)

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2012 Vol. 33, No. 3